French patent application (FR-91/01,193) describes a process for manufacturing a metallic tank which requires the use of metals of very high plastic strain of relatively high cost or of very low tensile strength.
The basic idea developed in the present invention is to use a press and a die for forming the metallic sheath, the die consisting, for its cylindric part, of a reinforced corrugated thermoplastic tube described previously in patent FR-2,553,860, the tube and the die fitting into each other after manufacturing, the metallic sheath for example being located inside the reinforced corrugated tube constituting the die.
The advantage of the new process according to the present invention is to use materials of average plastic strain and of a higher resistance than materials of very high plastic strain. The manufacturing cost is therefore decreased by using less material, a less costly material, and the final structure of the tank is lightened.